Drying milk.



UNI

ED ST *niv'r amen.

DRYING Minx.

To all whom it may concern:

'Be it known that I, JAMES ROBINSON FIAT-- MAKER, a citizen of the United States, residing at Paris, France, have invented new and useful Improvements. in Dr ing Milk, of which the following is a speci cation.

My present invention is an improvement in drying milk, whereby pure dry milk of improved quality can be obtained.

IIeretofore it haisuwen found necessary to modify natural mi k preliminary to dr ing it as, for example, by'addi'ng thereto oreign substances, in order to prevent the proteids of the milk from becoming insoluble during the drying rocess. All the dry milk heretofore made y exposing liquid milk in a thin layer or filnl upon a surface heated in excess 'of 212 F. and reducing it to d ness rapidly has been so insoluble in water t at the liquid milk reconstituted from it by the addition of water has shown a large deposit of milk constituents within a few minutes, unless the liquid milk from which it was obtained was reduced in acidity by the addition of some neutralizin agent. This fact is too well known in t e art to require further elaboration.

I have discovered that absolutel pure dry milk of practically natural solub' 'ty-from which liquid milk most closely resembling natural milk can be reconstituted by the simple addition of warm water-can be obtained from pure fresh milk in its natural state and without its being changed or modified in an way whatever if such natural milk is ex ose in a very thin film, upona' suitably [feated surface, for a eriod not exceedin two and one-half secon s in duration,.and t ereon reduced to practical dryness and then removed therefrom.

In practice, I prefer that the milk to be dried shall not remain exposed upon the heated dryin surface for a longer period than 2 secon s, and it is preferable in some cases that it should not be exposed more than one-half of a second. Generally speaking, in order to (get the least possible change in the containe proteids, the exposure should be as short as possible. It is very eas to obtain this exceedingly short exposure y employing rapidly-revolving drying cylinders as the drying surfaces, and I prefer to employ such cy inders, although I do not limit my process in its ap lication to the useof d ing cylinders,as at or otherwiseshaped rying surfaces may be used for the purpose. But

Specification of Letters Patent.

Application filed June 29, 1906. Serial No. 324,072.-

Patented m 11, 1909.

whatever apparatus is used-I prefer to arrange matters so that the exposed film of material is rapidly conveyed over some little distance during its short exposure upon the drying surface, as upon a rapidly revolving drying cylinder.

amwell aware'that milk has been dried heretofore upon revolving-(1r ing cylinders heated in excess of 212 F., lieing exposed thereon in a thin filin or layer, but the rate of revolution of such cylinders when used for that purpose has been so slow that the film or layer of milk has been exposed thereon much longer than 2% seconds-usually from 5 to 10 or more seconds. In the cases where milk has been dried on cylinders laced within a vacuum or a partial vacuum t e exposure has usuall been fora much longer time than 10 secon s. By drying milk by exposing it upon the heated drylng surface for less than, 2% seconds, I effect the operation so quickly that chemical action whereby the proteidsin milk are rendered insoluble b the .known processes, cannot take place: thus obtain pure dry milk-of-natural acidity and solubillty. I find this process of very limited exposure to be especially valuable also in drylng mixtures of milk and other substances such as mixtures of milk and eg s, mixtures of milk and sugar, starch, etc. t is not necessary that the milk to be dried by this process should be reviously condensed, although condensed m1 k can be dried b the process. I prefer to use milk that is abso utely natural and perfectly fresh and that has not been pasteurized or treated physically or chem lcally in any way. If twin-cylinder drying machines are used, the depth of the milk maintained between them s iould be kept as low as 'ossible so that it will not be injuriously-a ected by over-heating.

The process can be executedupon a single drying cylinder, any suitable means being provided for introducing the milk upon the said cylinder ina thin film and. for removing it therefrom within the time specified. Knives fixed and held in contact with the cylinder, I have found to 'be the best means for removing the film therefrom.

The time of exposure is the essence of my the time specified. The drying should be ellected in the free atmosphere and the temperature of the drying surface should be ke at above 270F. In practice I have found cylinders heated by 3;}- atmospheres of steam pressure to give excellent results. The milk being necessarily exposed in a very extended form, as in a thin film, the dry milk obtained is very light and flaky in form. It is distinguishable from the dry milks heretofore made by the fact that it has its natural acidity 'i. e. the acidity of the natural milk in dry form whereas the dry milk produced from milks which have been reduced in unnatural taste.

It is also perfectly- 1. lhe hereinbefore described process of drying milk which consists in exposing it in a very thin film, for a eriod of tune not exceeding two and onealf seconds, upon a suitable drying surface heated in excess of 270 F.

2. Thehereinbe'fore described process of drying milk whereby absolutely ure sterile dry milk of ractically natura solubility and of natural acidity is obtained, the said process consisting in exposing natural liquid milk, in a .yery thin film, for a period of time not exceedin two and one-half seconds, upon a suita le drying surface heated in excess of 270 F.

JAMES ROBINSON ll ATHAKER.

Witnesses ALBERT W. SioUssA, HENRY B. SOMMERVILLE. 

